yes similar, that was also my question 
I though I would try and make it clearer but I think I have failed. The 2nd example above is exactly what I’m looking for but when I deploy to ios, the mesh is black. The first one is also adequate, it works on IOS but it means I cannot change the background when I go deeper underground. I’m not sure why the first one works on IOS and the 2nd is black. Maybe you cannot have two masks on IOS?